Utility of area curve ratio electrocochleography in early Meniere disease.

Abstract

Electrocochleography (ECochG) is useful in supporting the diagnosis of Meniere disease (MD). Possible MD (early disease as defined by the 1995 American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium) is a readily treatable form of MD. To identify whether ECochG summating potential/action potential (SP/AP) area curve measures are more sensitive than conventional SP/AP amplitude ratios in detecting possible MD. A retrospective chart review of a 3-year period (1997-2000) was conducted. All charts of patients diagnosed as having MD who had undergone tympanic ECochG were examined to identify those with possible MD. Exclusion criteria were incomplete workup, ECochG performed using a prior system, cochlear microphonic spike obscuring ratio measurements, and prior otologic surgery. A control group of patients with normal SP/AP ratios and ECochG data were identified. SP/AP amplitude and area curve ratios for both groups were measured. Of 138 patients with MD reviewed, 20 (14%) had possible MD, and 8 passed exclusion criteria. An audiologist blinded to patients' diagnoses performed all measurements. The upper limit of normal for SP/AP amplitude and area curve ratios from the control group of ears (n = 13) (alpha =.05) were similar to previously published results. Of the 8 patients with possible MD, 4 had an abnormal SP/AP amplitude ratio, and 7 had an abnormal SP/AP area curve ratio; the difference between groups was statistically significant (P =.03, chi2). The SP/AP area curve ratio significantly improves ECochG diagnostic sensitivity in possible MD. This ECochG refinement will allow earlier intervention to preserve inner ear function in MD.